Filter tip for tobacco products



1957 M. O. SCHUR ErAL 2,801,638

FILTER TIP FOR TOBACCO PRODUCTS Filed May 11, 1954 V 2 Shets-Sheet 1 JNVENmRs. Milton 0. Schur BY Overron L. Hillsmun WW, ammjaafm filwmy ATTORNEYS FILTER TIP FOR TOBACCO PRODUCTS Filed May 11. 1954 2 Sheets-Sheet 2 FIG. 5

INVENTORS. Milton 0. hur

BYOverron L. lsmon ATTORNEYS FILTER TIP FOR TOBACCO PRODUCTS Milton 0. Schur, Asheville, N. C., and Overton L. Hillsman, Richmond, Va., assignors, by direct and mesne assignments, to The American Tobacco Company, New

York, N. Y., a corporation of New Jersey Application May 11, 1954, Serial No. 423,374 4 Claims. c1. 131-2es This invention relates to tobacco products, and more particularly to a filter tip for a smoking product, such as a cigarette.

Various proposals have been made for removing irritants from tobacco smoke to produce a cigarette from which the smoker would derive more enjoyment. When such proposals include the use of a filter, either built into the cigarette as a filter tip or formed as part of a cigarette holder through which the smoke is drawn, it is necessary that they do not attempt to remove too much from the smoke. The cigarette smoke must retain its basic characteristics to satisfy the smoker, and also if any attempt is made to remove too much from the smoke by a mechanical filtering operation, it impedes the flow of smoke to an objectionable extent, that is, it makes it difiicult for the smoker to draw on the cigarette.

Prior proposals include the construction of a filter tip by enclosing folded paper in a wrapper with longitudinal channels between the plies of the paper. Improved results are alleged to be obtained by creping the paper in a direction parallel to the longitudinal folds. It has also been proposed to place materials, such as flutfy asbestos or cotton, in alternate layers between convolutions of paper to provide a filter having superior characteristics and performance. Such filters, acting solely as mechanical filters, remove some solids, such as tars and thelike, but do not remove anything that is in the gaseous phase from the smoke. In the present invention we propose to form a filter tip consisting of a multitude of layers of paper with the paper substantially filling the wrapper in the tip portion of the cigarette, but providing a maze of tortuous passages which extend through the filter in a generally longitudinal direction. We also provide particles of activated charcoal in combination with the paper or fibrous material with the activated charcoal effectively dispersed throughout the paper, and the charcoal removes certain materials from the smoke which are present in gaseous form, and have not been removed heretofore to any importantextent by the mechanically functioning cigarette tips which have been used in the industry.

In carrying out the invention we preferably employ a paper Weighing not more than about 30 grams per square meter. The paper, when formed into the plurality of folds, weighs from 0.1 gram to about 0.3 gram per cubic centimeter. Best results are obtained if a pliant paper such as crepe paper or other paper having a rough surface such as embossed paper is utilized, particularly if the weight thereof is between about 16 grams and .30 grams per square meter. Ordinarily papers weighing from about 7 grams to 30 grams per square meter before creping and before crumpling are preferred.

It has been found advantageous in the case of cigarettes containing some blends of tobacco to use highly purified pump, for example, the so-called high alpha cellulose pulps of commerce, in the manufacture of the i United States Patent paper for the filtering medium in our filter plug. In

any event, the paper should be free from contaminants, whether naturally occurring or otherwise.

The activated charcoal must be incorporated with the fibrous material in such manner that it does not become deactivated. For instance, the utilization of glue or the like to secure the activated charcoal to a paper sheet is entirely unsatisfactory for the purpose since such materials tend to deactivate the charcoal and prevent its subsequent utility. It has been found in accordance with this invention that when a cellulosic fibrous material is utilized as the basis of a filter medium the activated charcoal can be included in the fiber furnish prior to or during the paper sheet formation without deactivating it, and the resulting sheet has the particles of charcoal secured to the individual fibers intermeshed through out the paper in such manner that the combined exposed surfaces provide improved filtering efliciency. This is of considerable advantage since, while other adsorbent materials, such as silica gel and the like, are efiective as filtering media, they do not lend themselves to either this method of incorporation with the fibrous material or to methods involving the use of adhesives or the like because they become deactivated. While the filter material of this invention may be utilized with any type of smoking device, it is particularly suited as a filter for cigarettes.

It is preferred, for best results, that the granulation of the activated charcoal be such that substantially all the particles thereof will pass through a Tyler screen having about 100 meshes per inch and substantially none of the particles will pass through a Tyler screen having about 300 meshes per square inch. The paper and the filter made from it tend to shed coarser particles while finer particles, though more securely held by the paper, are poorly retained during the papermaking process and r they tend to darken the filter excessively for a given concentration of charcoal. should contain from about 2.5 to about 60 percent by weight activated charcoal, with about 2'0 to 25 percent being the optimum amount for most filters.

In carrying out the invention, we have employed activated charcoal, such as Columbia Grade G, manufactured by The Carbide and Carbon Chemicals Company. This material, ground to a fineness of to 300 mesh, is added to the paper slurry in the proper cally. Thus if a light weight paper of less than about 16 grams per square meter is utilized, good filtration characteristics may be obtained if the only crumpling done is by the cone of a cigarette tip forming machine while the paper is being placed within the wrapper, as will be described in more detail hereinafter. With the heavier weight papers of the invention and preferably even with the lighter weight papers, however, it is preferable to crumple the paper by a process other than and in addition to the one by which it is inserted in the wrapper; Any crumpling process which forms a multitude of irregularly extending and irregularly spaced crumples may be utilized to advantage, but best results are obtained if the paper is crumpled by a process wherein it is com- Patented Aug. 6, 1957 For best results, the sheet paper The sheet may be creped, during manufacture,

or expand at least partially. A result similar to that desired is obtained by wadding or crushing a sheet of paper in the hand. Paper crumpled in this way is much softer and is inherently more pliant than before such mechanical working, probably because the bond between fibers has been loosened or the fibers have been partially pulled apart. A similar result is also obtained if the paper is heavily embossed before it is fed to the filter forming machine. Indeed, embossing is one of the preferred methods of preconditioning the paper for use in the manufacture of cigarette filters. In general, the greater the weight of the paper utilized, the more crumpling or other softening means required for optimum results.

A particularly advantageous method of crumpling the paper is to pull one or more sheets, ribbons or webs there- A of through a series of orifices, each orifice having lesser dimensions thanthe preceding one. By way of example, a set of three circular orifices arranged one after the other in the order of decreasing diameter in the ratio of about 0.25, 0.22 and 0.20 has been found admirably suited for the purpose. A greater or lesser number of orifices may be advisable with some papers, however, and the opening may be square, oval or of other shape adapted to crumple and to compress the paper as it is pulled therethrough. The tortuous passageways through the filter resulting from forming it from the crumpled paper insure that the smoke will impinge against the surface thereof as it passes through the filter.

The filter of this invention can be formed on a conventional cigarette making machine embodying modifications to adapt it for feeding the paper into the tip forming cone of the machine and for enclosing the layers of paper within the wrapper. The multitude of layers of paper may be formed from a single sheet of paper or from a plurality of sheets. When the heavier papers weighing about 16 grams or more per square meter are utilized, it has been found that even distribution of the layers within the wrapper is most easily approached if a plurality of sheets which have been separately crumpled before they are compressed together by the forming cone are utilized. Three separately crumpled sheets weighing about 16 grams per square meter compressed together in the forming cone of a cigarette machine make an advantageous filter.

If crepe paper is utilized best results are obtained if the direction ofcreping is transverse to the direction of flow of smoke through the filter. Preferably, the percentage crepe in the paper should be within the range of from' about 8 percent to about 60 percent. In other words, a sheet about inches long is reduced to a length in the range of from about 9.2 inches to about 4 inches when creped. The paper used to form the labyrinthal filter may be carried by the wrapepr as it is pulled through the forming cone of the cigarette making machine. The resulting plug may be cut into any convenient length and the intermediate product may be later cut to the required length for use in the smoking device.

In the accompanying drawings we have diagrammatically illustrated several organizations of apparatus elements that may be used in carrying out the process and making the product of our invention. In this showing: 7

i Fig. 1 is a diagrammatic perspective view illustrating one manner of forming the filter tip of our invention;

Fig. 2 is a perspective View of a cigarette including a filter tip of our invention;

Fig. 3 is a diagrammatic, perspective view of another 4 scribed, is provided with particles 2 of activated charcoal dispersed substantially uniformly throughout the sheet in the manner heretofore explained or in any other suitable manner. The sheet is preferably creped by conventional means.

In practicing the process with the apparatus of Fig. 1, a number of layers of these sheets, about one-half inch in width are mounted on a roll 3, and the activated charcoal containing strip 4 of multi-layers is delivered from the roll.

The paper from which the wrapper of the tip is to be formed is mounted on a roll 5, and it is also delivered from this roll in proximity to the strip 4 as indicated at 6. The wrapper paper 6 is pulled from roll 5 by endless belt 7 which passes over a plurality of suitably positioned rolls 8, one of which is mounted on a driven shaft. The belt passes through a tip-forming cone 9 of a conventional cigarette tip-making machine, and the strip 4 of the layers of paper with activated charcoal lying on the strip 6, is pulled through the cone with it. The pas sage through the cone forms the strip 6 into a convolutely wound wrapepr 10 with a vertical edge 11 to receive an adhesive. The strip 4 which has previously been worked to make it pliable is compressed as the strip 6 is wound into a tube, and the separate layers of the strip 4 are gathered forming a maze of tortuous passages 12 (Fig. 2) extending through the rod 10 in a generally longitudinal direction. The edge 11 of the rod 10 receives an adhesive from wheel 13, and this edge is then caused to overlap the other edge of the strip 6 and is sealed to it by the final forming cone 14. A heater 15 may be provided to remove water or other liquid from the adhesive and tightly seal the Wrapper of the rod 10. The rod is cut to desired lengths as indicated at 16 by a rotary cutter 17 or other suitable means. 7

The filter tip 16 and tobacco 18 are assembled in the outer cigarette paper 19, as illustrated in Fig. 2, in a conventional manner to form the completed cigarette.

An advantageous method of crumpling the paper of which the filter is formed is shown in Fig. 3 of the drawings. As shown, webs 20, 21, 22 of paper, which may be embossed or otherwise worked and-which contains dispersed particles of activated charcoal are fed from rolls 23, 24 and 25, respectively. Each of these webs ispassed through orifices in a succession of plates or dies 26, 27 and 28, each orifice being of smaller size than the preceding one. In a specific example we have employed circular orifices in which the diameter decreased in the ratio of approximately 0.25, 0.22, and 0.20. Thus orifices 29 in plate 26 are larger than the orifices 30 in plate 27 and the orifices 30 are, in turn, larger than the'orifices 31 in plate 28. H

A greater or lesser number of orifices may be employed and the openings 29, 30 and 31 may be of a shape which will crumple and compress the paper web as it is pulled through :the orifice. This crumpling produces the tortuous passages 12 when the paper is pulled through the forming cone. As shown, a web 32 is drawn through forming cone 33 to form a wrapper and compress the webs 20, 21 and 22 into a maze with the tortuous longitudinal passages as heretofore described in connectionwith Figs. land 2. The apparatus beyond the forming cone 33.may be the same, or similar to, that beyond the forming cone 9 of Fig. 1.

The plates 26, 27 and 28 are spaced apart a suffici'ent distance to permit the webs to expand after each crumpling before passing through the next orifice. The spacing may be in the nature of 3 or 4 inches. After passingth'rou'gh the orifices of plate 26 the webs expand as indicated at -34 before passing through the orifices of plate- 27. Likewise, after being crumpled by passing through the orifices of plate 27, the webs expand, as indicated at 35, beforepassing through the orifices of plate 28.

In the embodiment of the invention shown in Fig. 5 we start with a web or sheet of greater width. The web 36 is fed from a roll 37, and passes rotary slitters 38 by means of which it is cut into a plurality of strips of desired widths. These strips, which may have been previously creped, may then be passed through the dies of Fig. 3 to further work them, and increase their pliability, or they may be worked in any other suitable manner. One method of doing this, illustrated in Fig. 5, is by means of embossing rolls. As shown, we preferably employ two pairs of rolls. If in the first pair the positive roll 39 is the lower roll and the negative roll 40 the upper roll, the arrangement is reversed in the second pair with the positive roll 41 the upper roll and the negative roll 42 the lower roll. The pairs of rolls are spaced from each other, as heretofore described in connection with the dies or plates of Fig. 3 to permit the paper to expand after being embossed by the first pair of rolls, before it is fed through the second pair. The positive and negative surfaces for the rolls may be produced in many ways. The positive rolls 39 and 41 are roughened and this can be accomplished by way of example, by surfacing a roll with very coarse sandpaper. The surface of the negative rolls 40 and 42 should be of a soft material to permit the roughened surface of the positive roll to force the paper web into it. A layerof sponge rubber forms a satisfactory surface for these rolls.

While the use of the embossing rolls or the dies of Fig. 3 will usually provide sufl'icient working of the paper of which the filter is formed, particularly if the paper has been previously creped, we have illustrated plates 43, 44 and 45 having orifices (not shown) of decreasing size, similar to the orifices shown in Fig. 3 for further working of the paper. This may be desirable where a heavier material is employed. The several webs are superposed and fed with a web 46 of wrapper paper to a forming cone 47. As shown, web 46 is delivered from roll 48 by endless belt 49. Pasting wheel 13, final cone 14 and heater 15, heretofore described in connection with the apparatus of Fig. I, serve to complete formation of rod 50 which is then cut to suitable lengths for the formation of filter tips.

The filter tip heretofore described is not only an effective mechanical filter of the particulate constituents of tobacco smoke, without retarding the flow of smoke to an objectionable extent, but also acts as an adsorbent of other undesirable constituents of tobacco smoke. Owing to the high adsorption characteristics of activated charcoal our filter will remove constituents in gaseous form which are not removed by known filters that function by mechanical means only. Thus, large proportions of acrolein, an unsaturated aldehyde, and hydrocyanic acid are effectively removed by our filter. The concentrations of other saturated and unsaturated aldehydes, as well as ketones, are substantially reduced. Significant amounts of saturated and unsaturated hydrocarbons, both aromatic and aliphatic, are removed, as well as volatile acids.

Various types of activated charcoal may be used. In

addition to that previously mentioned, we have also employed Columbia grade ACX and Columbia grade SX, supplied by The Carbide and Carbon Chemicals Company. But other activated charcoals, which are obtainable in the desired degree of fineness, can be used in place of any of those mentioned.

By the term, activated charcoal, in the foregoing specification and in the appended claims, we mean to include activated carbon.

We claim:

1. A filter for smoking devices comprising a wrapper, and a filling of paper, weighing not more than 30 grams per square meter arranged in the wrapper in a multitude of layers to form a maze of tortuous passageways extending generally longitudinally through the filter, said paper having particles of activated charcoal predominantly of l0030() mesh dispersed therein and secured to individual fibers of the paper, the particles having active surfaces exposed to said passageways against which the tobacco smoke will impinge as it flows through the passages.

2. A filter for smoking devices comprising a Wrapper, and a filling of crumpled paper weighing not more than 7 to 30 grams per square meter arranged in the wrapper in a multitude of layers to form a maze of tortuous passageways extending generally longitudinally through the filter, said paper having particles of activated charcoal predominantly of l00300 mesh dispersed therein and secured to individual fibers of the paper, the particles having active surfaces exposed to said passageways against which the tobacco smoke will impinge as it flows through the passages.

3. A filter in accordance with claim 1 in which the paper contains from about 2.5% to by weight of activated charcoal.

4. A filter in accordance with claim 1 in which the paper contains from about 20% to 25% by weight of activated charcoal.

References Cited in the file of this patent UNITED STATES PATENTS 2,033,867 Segal Mar. 10, 1936 2,164,702 Davidson July 4, 1939 2,181,614 Streifiing Nov. 28, 1939 2,325,386 Frank July 27, 1943 FOREIGN PATENTS 290 Great Britain of 1863 538,529 Great Britain Aug. 7, 1941 188,399 Switzerland May 1, 1937 612,737 Germany May 3, 1935 OTHER REFERENCES Casey (text): Pulp and Paper," vol. I (1952), published by Interscience Publishers Inc, New York, page. 472 especially cited. 

1. A FILTER FOR SMOKING DEVICES COMPRISING A WRAPPER, AND A FILLING A PAPER WEIGHT NOT MORE THAN 30 GRAMS PER SQUARE METER ARRANGED IN THE WRAPPER IN A MULTITUDE OF LAYERS TO FORM A MAZE OF TORTUOUS PASSAGEWAYS EXTEND ING GENERALLY LONGITUDINALLY THROUGH THE FILTER, SAID PAPER HAVING PARTICLES OF ACTIVATED CHARCOAL PREDOMINANTLY OF 100-300 MESH DISPERSED THERIN AND SSCURED TO INDIVIDUAL FIBERS OF THE PAPER, THE PARTICLES HAVING ACTIVE SURFACES EXPOSED TO SAID PASSAGEWAYS AGAINST WHICH THE TOBACO SMOKE WILL IMPINGE AS IT FLOWS THROUGH THE PASSAGES. 